The impurities content in residual materials from building demolition or construction work or residual materials with visible impurities must be estimated by manually separating the particles of a residual granular material in order to determine the relative proportions by mass of each of the following 6 categories of particles, according to particle size fraction and percentage:
(3) crushed stone;
(4) cooked granular materials;
(5) light materials;
(6) other residual granular materials.
Classification by fraction must be accomplished using 2.5 mm, 5 mm, 10 mm, 20 mm, 31.5 mm, 56 mm and 112 mm screens that comply with ISO 3310-1, Test sieves – Technical requirements and testing – Part 1: Test sieves of metal wire cloth. Before separation by screening, samples must be dried in an oven of sufficient size that can be maintained at a constant temperature of 50ºC ± 5ºC for residual granular material containing asphalt and 110ºC ± 5ºC for other materials.
The steps in the process are as follows:
(1) separate by screening the entire sample and retain the fraction withheld by the screens;
(2) before preparing the test portions, determine the relative percentages of the fractions using the screens, calculated as in the following example for the 2.5 – 5 mm fraction (P2.5-5):
P2.5 - 5 (%) = (mass withheld by 2.5 5 mm screen (g)) ÷ (total mass withheld by 2.5 mm screen (g))
(3) based on the maximum particle size of the residual granular material, reduce the fractions and record the minimum masses of the test portions in table form based on the masses indicated in the following table:
|Maximum particle size (mm)||Minimum mass of the test portions by fractions|
|2.5 mm||5 - 10 mm||10 - 20 mm||20 - 31.5 mm||31,5 - 56 mm||56 - 112 mm|
|31.5||30 g||200 g||500 g||1,000 g|| || |
|56|| || || || ||3,000 g|| |
|112|| || || || || ||8,000 g|
(4) spread each fraction in a layer at the bottom of an aluminum or stainless steel container of a shape and size that allows the residual granular material to be spread out in a thin layer. Use as many containers as there are fractions to be analyzed;
(5) for each fraction, visually inspect the particles and classify them into the 6 categories of above-mentioned constituents;
(6) weigh them using a scale with a 20,000 g capacity, accurate to 1 gram, and record the mass of each category of particles by fraction in a table of results;
(7) calculate the percentage of residual granular material by category using the following equation, for which the terms are defined in the table below:
|Fraction (in mm)||Percentage related to the fraction in the residual granual material||Mass tested (kg)||Mass of impurities categories (kg)|
|Cooked granular materials (CM)||Light materials (LM)||Other residual granluar materials (OM)|
(8) the sum of the percentages of residual granular materials in the “cooked granular materials” and “light materials” categories and of the other residual granular materials corresponds to the percentage by weight of the impurities content, and the percentage of the “light materials” category corresponds to the percentage by weight of light materials.